The relationship between the joint effect of C-reactive protein and glycated hemoglobin with the risk of depressive symptoms among middle-aged and older adults: Findings from the China health and retirement longitudinal study

The present study aimed to explore the relationship between the joint effect of C-reactive protein and glycated hemoglobin with the risk of depressive symptoms among middle-aged and older adults.A total of 5985 participants aged 45 years or older from the China Health and Retirement longitudinal study 2011 and 2015 were included in this study. Participants were divided into 4 groups according to C-reactive protein and glycated hemoglobin. Multivariate logistic regression model was used to explore the associations between C-reactive protein and glycated hemoglobin and new-onset depression.During the follow-up period, 1001(16.73%) participants experienced depressive symptoms. Compared to participants with low C-reactive protein and low glycated hemoglobin, individuals with C-reactive protein and glycated hemoglobin both high levels have a higher risk to suffer from depressive symptoms with corresponding multivariable adjusted odds ratio (OR = 1.17, 95% CI: 1.01-1.36). Adding C-reactive protein and glycated hemoglobin simultaneously to conventional risk model significantly improved risk reclassification for depressive symptoms. The statistically significant interaction with joint effects of C-reactive protein and glycated hemoglobin on depressive symptoms was only found in different sex (P-interaction = 0.006) or age (P-interaction = 0.004) groups. Sensitivity analysis yields similar results.Higher levels of C-reactive protein and glycated hemoglobin jointly increased the risk of depressive symptoms among Chinese middle-aged and older adults. Using the combination indicator of C-reactive protein and glycated hemoglobin could better identify individuals at risk of depressive symptoms.